The aim of this study was to evaluate the effect of mechanical cycling on the biaxial flexural strength of two densely sintered ceramic materials.Disc shaped zirconia (In-Ceram Zirconia) and high alumina (Procera AllCeram) ceramic specimens (diameter: 15mm and thickness: 1.2mm) were fabricated according to the manufacturers’ instructions. The specimens from each ceramic material (N=40, n=10/per group) were tested for flexural strength either with or without being subjected to mechanical cycling (20,000cycles under 50N load, immersion in distilled water at 37°C) in a universal testing machine (1mm/min). Data were statistically analyzed using two-way ANOVA and Tukey's test (α=0.05).High alumina ceramic specimens revealed significantly higher flexural strength values without and with mechanical cycling (647±48 and 630±43MPa, respectively) than those of zirconia ceramic (497±35 and 458±53MPa, respectively) (p<0.05). Mechanical cycling for 20,000 times under 50N decreased the flexural strength values for both high alumina and zirconia ceramic but it was not statistically significant (p>0.05).High alumina ceramic revealed significantly higher mean flexural strength values than that of zirconia ceramic tested in this study either with or without mechanical cycling conditions.